11 December, 2015

Finally got rid of the pirated USB chips for the UV-5R and the AP510

Both the Baofeng UV-5R handheld UHF/VHF radio and the Sainsonic AP510 APRS tracker come with interface cables with pirated chips. These are clones of Prolific USB/serial chips. Since Prolific has taken measures against this, only old drivers will work with them. That means that one has to stop automatic driver updates as explained on the Miklor site for the Baofeng UV-5R. The same is true for the AP510. This is a nuisance.

I got tired of this and got myself some USB/serial modules from Ebay based on the CP2102 chip instead. The cost was US $1.43 a piece so it should be affordable for anyone. I also got some clear heat shrinkable tube.

19 November, 2015

Curing amnesia in the 10 MHz GPS reference

Just good enough 10 MHz GPS reference with
u blox Neo-7M GPS module to the upper right,
10 MHz output buffer lower right,
USB interface to the upper left,
CR2032 lithium battery center left,
GPS antenna in the center,
and SMA output connector lower left.
My "just good enough 10 MHz GPS reference" which drives the external clock input on my Elecraft K3 kept losing its configuration if power was off for a day or so. I have therefore fitted a CR2032 3V lithium battery as seen to the left in this image.

It is connected in series with a 1N4148 diode in order to prevent attempts at charging the lithium cell. The connection goes to pin 22 (V_BCKP) as described by G4ZFQ on his website. The diode is visible to the upper left of the battery.

With this, I consider the 10 MHz reference to be finished.

Other related posts:

02 November, 2015

Radio Ghosts Have Haunted the Airwaves for Nearly a Century

“The starship hypothesis is a very interesting one, and the one which seems to be the most popular one on the internet,” said Sverre Holm, a professor of signal processing at the University of Oslo. “Such theories always excite our imagination, but it builds on a very poor data set. Unfortunately I believe it says more about human imagination than anything else.”

Although scientists have yet to settle on a final explanation for these mysterious echoes, Holm believes this is has less to do with a lack of scientific knowledge than a lack of willpower.

“I think that with today’s satellites and sensors, the mystery of Long Delayed Echoes (LDEs) could probably be solved,” he said. “What’s holding us back is most likely the problem is not considered important enough—it doesn’t occur often enough and doesn’t affect important enough forms of communications.”

These are excerpts from an interview in an article entitled "Radio Ghosts Have Haunted the Airwaves for Nearly a Century" on Motherboard Vice written by Daniel Oberhaus. It builds on a web page that I created some years ago after having spent days studying the archives from the 20's of professor Carl Størmer at the National Library in Oslo.

15 October, 2015

Better with SMA

I had some trouble closing the lid on the "Just good enough 10 MHz GPS reference" due to the size of the BNC jack. Therefore I changed it to an SMA (SubMiniature version A) female jack. A thin cable connects it to the K3's SMA input and there is no need for any SMA-BNC adapter on that end.

At the same time I moved the GPS antenna to a more central location in the tin, in the hope that the walls of the tin would interfere less with GPS reception. That's the theory anyway, if it matters much in practice is a different story.

Actually, I think I'm going to use SMA more often with these clear top tins and also Altoids tins. They take up much less space and are easier to install and to work with.

There aren't any high power applications for circuitry in such tins, so I cannot so any reason why the SMA won't work just as well or even better than the BNC.

Other related posts about the 10 MHz reference:

03 October, 2015

Just good enough 10 MHz GPS reference

Some time ago I noticed that the Ublox Neo-7M GPS has a 10 MHz output which is locked to the GPS system's accuracy. Most people kept saying how useless it was due to excessive jitter unless it was cleaned up with a phase locked loop of some sort.

At about the same time I installed the external reference input for my Elecraft K3. The K3EXREF enables the K3's frequency to be locked to an external 10 MHz reference. What struck me was how its function is described:

This got me wondering if the Neo-7M would be just good enough as a reference and that all the averaging internally to the K3 would take care of the jitter.

11 August, 2015

The LM386 Pixie challenge

The Pixie 2 is this minimal transceiver which I and many others have played around with and had lots of fun with. My 80 m version is shown below, but right now it is very popular with some incredibly cheap Chinese ones on sale on Ebay and other places.

The Pixie 2 uses the versatile LM386 amplifier for its audio output. I have shown previously on this blog how its gain can be boosted and how it can implement a CW filter, and also how the muting can be improved. However, during transmission, the LM386 just sits there idle, although it can be used to amplify a sidetone from an external oscillator.

But I'm sure the old 70's LM386 can do better than that. Despite its age, recently some pretty amazing uses of this chip have been demonstrated. It can be used as a regenerative receiver at least up to medium wave frequencies and it can also be used as an envelope detector/demodulator.

The LM386 challenge is this: Is is possible to implement a sidetone oscillator for the Pixie using only the LM386 with as few other components as possible? The output level needs to be controllable in order to make it comparable to that of the Pixie in the receiver mode.

The best data sheet for the LM386 seems to be the one for NJM386 from New Japan Radio Co. It is, as far as I know, the only one which shows the various muting circuits including the one using pin 7 which I have explored. It also shows the LM386 as an oscillator: both a sinusoidal and a square wave one.

In order for the LM386 to be useful as a sidetone oscillator, I believe that the oscillation must take place in the input circuitry. That seems to be the only way to ensure that the output doesn't come out at a blasting full rail-to-rail swing as in the square wave oscillator example in the data sheet.

By the way, the data sheet referred to above is also the basis for the improved Spice model for the LM386 that just was developed. It came partly as a response to my complaint over how poor the present one was. Maybe the new Spice model, developed by EasyEDA, could help solve the LM386 challenge?

11 July, 2015

Regenerative receiver based entirely on the LM386

I got a tip the other day that there is an interesting circuit over at the RadioBoards Forum where an LM386 IC is used as a regen receiver for the medium wave band. It is the user 'Selenium' who has come up with that circuit. I think it is quite an amazing application of this IC - so here it is:
LM386 as a medium wave regen receiver by user Selenium on RadioBoards Forum

Interestingly, both the + and - inputs are tied together (pins 2 and 3). It is also quite unusual to connect pin 7 to anything but capacitors (for bypass or extra input as I have done), so that may change the bias of the input stage. Further, the smaller the impedance from pin 1 to ground, the larger the gain (here 10 uF in series with 1k for low frequencies and 100 pF for high frequencies).

If you want to read more about the regen circuit, go to the RadioBoards Forum here.

06 June, 2015

CQ WPX made my day

From time to time I have heard of those of who manage to contact 100 DXCC countries during one weekend. This past weekend it was my turn to try.

If you have a contest station with 1 kW and monoband yagi antennas, then this goal shouldn't be too hard. But for my station with only an 80 m horizontal loop (loop skywire) circling its way through my garden from treetop to treetop and 100 W of transmitter power from my K3, the challenge was greater.

About 6 hours before the end of the test and with 87 countries, I had almost given up so I sent the tweet above. The status for the second day of the contest was that I had only worked two more countries.

But then in the final hours I heard and then contacted Tunisia, Malaysia, Australia og Kosovo (Z6) to bring me to 91, and then Laos and Albania. But then it took a long while for some new ones: Spanish Africa (EA9) and Argentine. I also managed two more Caribbean stations (J3 and CO) and Peru and Sardinia.

Finally in the last hour of the contest two more Caribbean stations (PJ2 and VP9) and in the end Mexico 21 minutes before the end of the contest. That brought the total to 102. I think that was needed as Kosovo isn't really an approved country and I also had contact with what was probably a pirate and not a station from Andorra. That signature was C31XR which most likely is the name of an antenna and not a real station.

My total was 47 European countries, 19 from Asia, 12 from North America, 10 from Africa, 9 from South America and 3 from Oceania. I think it helps to be in Europe as I had almost half of the countries quite close by, but it would be interesting to hear comments from North Americans on how realistic they consider this goal to be from their location.

23 May, 2015

Where can I get APF and DIV stickers for my K3?

The updated Elecraft K3, the K3S, has some nice improvements that would be nice to have, but which I also can live fine without. But even an old K3 can be updated to some of these improvements. They are detailed on the Elecraft K3S FAQ.

I studied the front panel for differences and put red rings around them. The three to the upper left have to do with the new display bezel with silver instead of black screws, the S in K3S, a built-in marker for the VFO A knob, and a soft-touch VFO A knob.

In addition to the marking with OFS (offset) to the left of the RIT/XIT control, there are two markings that also reflect what my present K3 with the latest firmware does:
  • APF instead of DUAL PB (Audio Peaking Filter - Dual Passband) - upper right
  • New marker for DIV - Diversity reception - to the left of VFO A
It sure would be nice to get stickers with APF and DIV to put on mine!

17 May, 2015

The ultimate WSPR spot

A spot reported by K1JT must be the ultimate goal for the WSPR mode. K1JT, Joseph Taylor, is the Nobel laureate who first developed this mode and other related two-way modes like JT65 and JT9.

My 0.1 W 21 MHz WSPR transmitter regularly makes it over the Atlantic, but never before to K1JT. The SWR was something like 7:1, but apparently that works fine, both for the transmitter and for radiation.

The antenna is a 13 m doublet oriented with the broadside facing East-West (the EU spots in the figure are from my Ultimate 3 on 21 MHz with another antenna and at another location). I feed the doublet with 450 ohm ladder line to a 4:1 Elecraft balun which is connected to the Ultimate 2 transmitter.

07 May, 2015

Ultimate software is up to date

As I have mentioned several times on this blog, I have thoroughly enjoyed WSPR modes ever since Hans, G0UPL came out with the first Ultimate QRSS/WSPR kit.

That means that I have three different versions of the kit. Since Hans has kept on updating the software and even published the compiled versions, it is also possible to upgrade even the old ones.

I have done that and the displays here show the Ultimate 3, the Ultimate 2, and the Ultimate 1 with the latest software.

It is possible to upgrade the chips in-circuit, but I found that it is simpler to remove the chip temporarily from the socket and move it to a simple veroboard with crystal oscillator components. It is connected to my Ebay version of the USBtinyISP.

29 April, 2015

First 475 kHz WSPR decoding

Tonight I made the first successful decoding of WSPR on the 630 m band. What inspired me was all the talk on the Elecraft reflector on the new synthesizer which in addition to having less phase noise, also allows the K3 to go below 500 kHz. I don't have that synthesizer, but the discussion reminded me of the low frequency converter I built many years ago. It converts 0-1 MHz to 14-15 MHz. Using the KXV3 transverter interface of the K3 it was easy to interface and get up and running.

The first signals I decoded are shown in the water fall above, and their origin in Germany and the Netherlands is shown in the next figure.

According to WSPRnet, PA0A's 2 Watt transmitter is 784 km away from me, and DK7FC's 1 Watt is 1164 km away.

The converter is quite simple and is based on a 74HC4053 switch used as a mixer with a 74HC04 for a 14 MHz oscillator. It is the design of SM6LKM, but with a different oscillator frequency and a simplified output filter compared to his. It is one of many small projects that I have built in Altoids tins.

The antenna used was my trusty old 80 meter horizontal loop which has been the main work horse for making my 8-band DXCC (more than 100 countries on all bands 3.5 - 28 MHz) possible. It is fed with ladderline into a 4:1 Elecraft balun in the shack.

Perhaps the next step is to finish the 475 kHz filter of my Ultimate 3 WSPR transmitter and see if others can receive me? That is going to be more of a challenge antenna-wise.

15 April, 2015

A beauty of a crystal radio

This past weekend during Hammeeting - the largest Ham rally in Norway - I met Per LA9DTA.

He showed me his beautiful crystal radio. It can be seen in the center of the table, with some close-ups below. The design has a printed coil and the whole design is made on a PCB which was shaped as shown in the image. It has a bandswitch and a Soviet low forward voltage Ge diode.

I fell for his design, but with the lack of longwave and medium wave transmitters here I am not sure if I would have much use for it. That is unless I set up one of my transmitter projects to support a radio like this.

I was demonstrating WSPR with my Ultimate 3 transmitter. It can be seen on the right hand side of the table. I wanted some fresh spots as I was giving a presentation later that day entitled "WSPR, JT65, JT9: Digital modes by Nobel laureates K1JT for HF DX with simple equipment". As I was spotted both on 40 m and 80 m I was happy with the performance. Per had also brought his Ultimate 3. Not the modified 11-band version, but just a plain one this time.

08 April, 2015

Car upgrade to LEDs

It was time to upgrade the interior lights in my 2004 Volvo. I got some lamps from Ebay specified as 42 mm LED Festoon, 80-85 lm, 12V. As many others have experienced also, they kept on glowing faintly after the door was closed. But when the ignition was turned off the lamps were completely off also, so there was no danger of draining the battery. Still this is not the way one expects lamps to behave.

One can get more expensive LED lamps which avoid this faint glow, "Canbus error free" seems to be the way to specify this. But mine were of the plain type, and the problem seems to be the leakage current in the FET switches that turn the lights on and off. It is tiny, but enough to give a voltage large enough to turn the LEDs on. An additional resistor load will lower the voltage below that threshold.

02 April, 2015

All continents in one night on WSPR

For me South America, Australia, and Africa are quite rare on WSPR. But they all heard my tiny 0.2 W signal the night between 31 March and 1 April in addition to North America, Asia and Europe. That's a new one for me and worthy a brag post on the blog, I think! Hopefully, it may also inspire others to try low power WSPR.

In Australia and South America I was heard on the 10 MHz band, in Africa on 21 MHz, in Pakistan on 14 MHz, while 7 and 10 MHz worked into Siberia. North American stations also heard me on the 7 and 10 MHz bands.

This was on my untuned 80 m horizontal loop fed with open-wire feeder and a 4:1 balun. This shows both that the bare-foot Ultimate 3 kit is very tolerant of loads with SWR much different from 1, and that WSPR gives amazing results.

31 March, 2015

Low power longwave transmitter experiment

Many places in the world, low power transmitters in the medium wave band are allowed. I am talking about regulations like in the US where FCC part 15 allows up to 100 mW input.

In Norway we have a particular permission for members of the Norwegian Radio Historic Society to transmit up to 500 mW on 216 kHz in the longwave band. I'm not sure if this is output or input power [it's output power]. The permission is meant to cover a personal collection of historic radios. The frequency is the one used by the main transmitter north of Oslo from 1954-1995 running 200 kW. The frequency is still allocated to Norway, so I guess that is why we may use it this way.

09 February, 2015

Finally got my Ultrafire WF-501B as I wanted it

As I wrote in my blog post a few days ago, I got the intensity down for night vision for my red flashlight. But I wasn't quite happy with the level and wanted to reduce it even more. To do that I had to unsolder 6 of the 8 AMC7135 350 mA constant current ICs on the PCB of the AMC7135*8 2800mA 4-Group 5-Mode Circuit Board.

These constant current chips are all run in parallel with the VDD input for control. The 8-pin Atmel ATtiny13A chip controls all VDD inputs in parallel from its pin 6. When the VDD pin is low there will be no light. I haven't measured this, but I am assuming that this pin is pulsed in order to reduce current down from the maximum.

My measurements for the High, Medium, and Low settings are:

04 February, 2015

Dimming my Ultrafire WF-501B

I got this red LED flashlight as a Christmas present. But unfortunately the intensity was way too high for what I intended to use it for. A soft red light preserves your night vision, and is ideal for use with a telescope in the dark as was my intention. But if the intensity was as high as before the modification, night vision would suffer anyway.

I then found this YouTube video describing how the controller circuit board could be replaced by one with more functions. As recommended I therefore ordered an AMC7135*8 2800mA 4-Group 5-Mode Circuit Board with 8 AMC7135 current regulators in parallel. The image shows the original circuit board as connected before the modification in the front in the image and the new one behind it.

The new board gave me the choice of one of 4-groups:
  1. 3-mode: Lo (5%) - Hi (100%) - Strobe
  2. 3-mode: Lo (5%) - Mid (30%) - Hi (100%)
  3. 2-mode: Lo (10%) - Hi (100%)
  4. 5-mode: Lo (5%) - Mid (30%) - Hi (100%) - Strobe - SOS

30 January, 2015

- Hardly any young people are becoming hams anymore

This is what Ed Muns, W0YK, said in an interview the other day, and goes on with "because they see this as kind of old school stuff."

A year ago the ARRL web site said: "Amateur Radio showing steady growth in the US". AH0A's website with statistics over the US ham population backs this up with the curve shown here. Even in my local club we are now seeing young people signing up for licence classes. 

How different perspectives! How has an old radio amateur like W0YK come to believe in the myth of declining numbers of hams?

27 January, 2015

0.2 Watts to South Africa

This is a new one for me: Norway-South Africa on 30 m WSPR in the middle of the night. Again I am amazed at what this mode can accomplish, and also what my little Ultimate 3 kit is able to do. 

The antenna used on my side was my trusty old 80 m long horizontal loop fed with a 4:1 balun and no tuning beyond that (SWR 7:1). Output power was from a single stage BS170 driven at 5 Volts, or about 200 mW in a 50 ohms load. In this particular antenna, the output is most likely much lower. 

ZS6KN is the only non-European station who has heard me this night on 30 m, with a marginal SNR of -27 dB.